felix642 created this revision.
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The following code is safe and should not trigger the warning
constexpr std::size_t k1Mb = 1024 * 1024;
Fixes #64732
Repository:
rG LLVM Github Monorepo
https://reviews.llvm.org/D158338
Files:
clang-tools-extra/clang-tidy/bugprone/ImplicitWideningOfMultiplicationResultCheck.cpp
clang-tools-extra/docs/ReleaseNotes.rst
clang-tools-extra/test/clang-tidy/checkers/bugprone/implicit-widening-of-multiplication-result-int.cpp
Index:
clang-tools-extra/test/clang-tidy/checkers/bugprone/implicit-widening-of-multiplication-result-int.cpp
===================================================================
---
clang-tools-extra/test/clang-tidy/checkers/bugprone/implicit-widening-of-multiplication-result-int.cpp
+++
clang-tools-extra/test/clang-tidy/checkers/bugprone/implicit-widening-of-multiplication-result-int.cpp
@@ -107,10 +107,28 @@
long n14(int a, int b, int c) {
return a + b * c;
}
+
long n15(int a, int b, int c) {
return a * b + c;
}
+unsigned long n16()
+{
+ return (1024u) * 1024;
+}
+
+long n17(int a) {
+ return a + 1024 * 1024;
+}
+
+long n18(int a)
+{
+ return (a * 1024);
+ // CHECK-NOTES-ALL: :[[@LINE-1]]:11: warning: performing an implicit
widening conversion to type 'long' of a multiplication performed in type 'int'
+ // CHECK-NOTES-ALL: :[[@LINE-2]]:11: note: make conversion explicit to
silence this warning
+ // CHECK-NOTES-ALL: :[[@LINE-3]]:11: note: perform multiplication in a wider
type
+}
+
#ifdef __cplusplus
template <typename T1, typename T2>
T2 template_test(T1 a, T1 b) {
Index: clang-tools-extra/docs/ReleaseNotes.rst
===================================================================
--- clang-tools-extra/docs/ReleaseNotes.rst
+++ clang-tools-extra/docs/ReleaseNotes.rst
@@ -173,6 +173,10 @@
<clang-tidy/checks/bugprone/reserved-identifier>`, so that it does not warn
on macros starting with underscore and lowercase letter.
+- Improved :doc:`bugprone-implicit-widening-of-multiplication-result
+
<clang-tidy/checks/bugprone/bugprone-implicit-widening-of-multiplication-result>`
+ check to ignore false-positives with integer literals.
+
- Improved :doc:`bugprone-lambda-function-name
<clang-tidy/checks/bugprone/lambda-function-name>` check by adding option
`IgnoreMacros` to ignore warnings in macros.
Index:
clang-tools-extra/clang-tidy/bugprone/ImplicitWideningOfMultiplicationResultCheck.cpp
===================================================================
---
clang-tools-extra/clang-tidy/bugprone/ImplicitWideningOfMultiplicationResultCheck.cpp
+++
clang-tools-extra/clang-tidy/bugprone/ImplicitWideningOfMultiplicationResultCheck.cpp
@@ -34,6 +34,13 @@
return BO->getLHS()->IgnoreParens();
}
+static bool hasIntegerLiteralOperators(const Expr* E)
+{
+ const auto *BO = dyn_cast<BinaryOperator>(E);
+ return isa<IntegerLiteral>(BO->getLHS()->IgnoreParenImpCasts()) &&
+ isa<IntegerLiteral>(BO->getRHS()->IgnoreParenImpCasts());
+}
+
ImplicitWideningOfMultiplicationResultCheck::
ImplicitWideningOfMultiplicationResultCheck(StringRef Name,
ClangTidyContext *Context)
@@ -89,6 +96,10 @@
if (!LHS)
return;
+ // Widening multiplication on Integer Literals.
+ if(hasIntegerLiteralOperators(E))
+ return;
+
// Ok, looks like we should diagnose this.
diag(E->getBeginLoc(), "performing an implicit widening conversion to type "
"%0 of a multiplication performed in type %1")
Index: clang-tools-extra/test/clang-tidy/checkers/bugprone/implicit-widening-of-multiplication-result-int.cpp
===================================================================
--- clang-tools-extra/test/clang-tidy/checkers/bugprone/implicit-widening-of-multiplication-result-int.cpp
+++ clang-tools-extra/test/clang-tidy/checkers/bugprone/implicit-widening-of-multiplication-result-int.cpp
@@ -107,10 +107,28 @@
long n14(int a, int b, int c) {
return a + b * c;
}
+
long n15(int a, int b, int c) {
return a * b + c;
}
+unsigned long n16()
+{
+ return (1024u) * 1024;
+}
+
+long n17(int a) {
+ return a + 1024 * 1024;
+}
+
+long n18(int a)
+{
+ return (a * 1024);
+ // CHECK-NOTES-ALL: :[[@LINE-1]]:11: warning: performing an implicit widening conversion to type 'long' of a multiplication performed in type 'int'
+ // CHECK-NOTES-ALL: :[[@LINE-2]]:11: note: make conversion explicit to silence this warning
+ // CHECK-NOTES-ALL: :[[@LINE-3]]:11: note: perform multiplication in a wider type
+}
+
#ifdef __cplusplus
template <typename T1, typename T2>
T2 template_test(T1 a, T1 b) {
Index: clang-tools-extra/docs/ReleaseNotes.rst
===================================================================
--- clang-tools-extra/docs/ReleaseNotes.rst
+++ clang-tools-extra/docs/ReleaseNotes.rst
@@ -173,6 +173,10 @@
<clang-tidy/checks/bugprone/reserved-identifier>`, so that it does not warn
on macros starting with underscore and lowercase letter.
+- Improved :doc:`bugprone-implicit-widening-of-multiplication-result
+ <clang-tidy/checks/bugprone/bugprone-implicit-widening-of-multiplication-result>`
+ check to ignore false-positives with integer literals.
+
- Improved :doc:`bugprone-lambda-function-name
<clang-tidy/checks/bugprone/lambda-function-name>` check by adding option
`IgnoreMacros` to ignore warnings in macros.
Index: clang-tools-extra/clang-tidy/bugprone/ImplicitWideningOfMultiplicationResultCheck.cpp
===================================================================
--- clang-tools-extra/clang-tidy/bugprone/ImplicitWideningOfMultiplicationResultCheck.cpp
+++ clang-tools-extra/clang-tidy/bugprone/ImplicitWideningOfMultiplicationResultCheck.cpp
@@ -34,6 +34,13 @@
return BO->getLHS()->IgnoreParens();
}
+static bool hasIntegerLiteralOperators(const Expr* E)
+{
+ const auto *BO = dyn_cast<BinaryOperator>(E);
+ return isa<IntegerLiteral>(BO->getLHS()->IgnoreParenImpCasts()) &&
+ isa<IntegerLiteral>(BO->getRHS()->IgnoreParenImpCasts());
+}
+
ImplicitWideningOfMultiplicationResultCheck::
ImplicitWideningOfMultiplicationResultCheck(StringRef Name,
ClangTidyContext *Context)
@@ -89,6 +96,10 @@
if (!LHS)
return;
+ // Widening multiplication on Integer Literals.
+ if(hasIntegerLiteralOperators(E))
+ return;
+
// Ok, looks like we should diagnose this.
diag(E->getBeginLoc(), "performing an implicit widening conversion to type "
"%0 of a multiplication performed in type %1")
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